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Патент USA US3087417

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April 30, 1963
Filed Sept. 11, 1959
the diffuser.
Eugene F. Averill, Waterloo, and Harold E. Strauh, Cedar
Falls, Iowa, assiguors to Titus Manufacturing (Iorpora
tion, Waterloo, Iowa, a corporation of Iowa
Filed Sept. 11, 195?, Ser. No. $39,332
4 Claims. (Cl. 98-418)
This invention, in general, relates to improvements in
ceiling and wall diffuser outlets and, more particularly,
to improvements for the purpose of minimizing the de
posit of dirt and the like on ceilings and walls sur
rounding the diffuser outlet.
Dirt deposit on surrounding wall and ceiling areas is
Patented Apr. 36, 1963
In this manner the lower velocity secondary
air jet adjacent the ceiling serves to isolate the ceiling
area surrounding the diffuser from the main jet and the
room air mixed therewith by induction.
A preferred embodiment of the invention is illustrated
in the drawing wherein:
FIG. 1 constitutes a bottom plan view of a ceiling
diffuser mounted in a ceiling; and
FIG. 2 is a partial side elevation of the diffuser of
FIG. 1, with a portion thereof being shown in section
taken ‘along lines 2—2 of FIG. 1.
In the drawing, the numeral 1 designates the vertical
take-off duct of an air distribution system which sup
plies supply air to the ceiling diffuser of outlet designated
a problem common to all air distribution systems. These 15 generally at 2. The diffuser 2 is mounted in a hole 3
cut in plastered ceiling 4. The ceiling air diffuser com
dirt deposits cause streaking or graying of the wall areas
and, after prolonged operation of the air distribution sys
tem, these dirty areas become unsightly. The primary
source of the dirt deposited on the ceiling areas is not,
as one might expect, from the air discharged from the
air distribution system, wherein it is usually ?ltered or
otherwise cleaned, but rather the major source of the
dirt is in room air. The room air is picked up by the air
stream ?owing out of the diffuser outlet, and the dirt in the
room air is carried outwardly along the ceiling or wall
areas with the primary air stream of the diffuser outlet.
A portion of the dirt picked up from the mixing of the
room air with the primary air stream of the diffuser even
tually is deposited on the ceiling and the wall area sur
rounding the diffuser outlet.
Therefore, it will be seen that the installation of effi
cient ?ltering or other air cleaning systems in the air
distribution system will not completely solve the dirt
deposit problem. The alleviation of dirt deposit on wall
prises an outer ring 5, which may be a stamped metal
or the like, having a cylindrical portion 6 forming a
neck at the upstream side of the diffuser. Forwardly of
the neck portion 6 is a radially outwardly ?aring por
tion 7 of a trumpet shape and forming a convex front
face. The trumpet shaped, radially outwardly ?aring
portion 7 merges with a radially outwardly extending
portion 8 forming a concave forward face, and the ra
dially outwardly extending portion 8 terminates in a rear
wardly directed peripheral portion 9 which abuts with
the ceiling 4.
The ceiling diffuser 2 is rigidly mounted by means
of sheet metal screws 10. The neck portion 5 of the
diffuser has spot welded thereto three radially inwardly
extending spider arms 11, 12, 13, equally spaced and
extending radially inwardly toward the center of the dif
fuser. The remaining portion of the diffuser constitutes
a center de?ector cone 14 which is spot welded to the
areas surrounding the diffuser outlet must be solved 35 lower end v11.5 of the spider arm on the rear of disc
by something other than ?ltering of the air stream of
16 of the center de?ector cone 14. The remainder of
the air distribution system inasmuch as the presence of
the center de?ector cone constitutes a trumpet shaped
dust particles, smoke and the like are inevitable in room
?aring portion 17 which forms an air de?ector sur
The mixing of the room air from the diffuser outlet
with the discharged air stream, which mixing will herein
after be referred to as induction of the room air by the
discharged air stream, is much greater when the velocity
face for de?ecting the supply air stream supplied to
‘the dilfuser in a radially outward direction.
'The diffuser may have additional de?ector members
mounted concentrically with the center de?ector cone.
In the embodiment illustrated in the drawing, one addi
of the air stream emitted from the diffuser outlet is 45 .tional de?ector member for de?ecting the supply air
high than when said velocity is low. This phenomenon
is believed to be due to the fact that therfaster moving
stream is shown, although additional de?ector members
may be employed where needed. In the embodiment
illustrated, there is mounted on depending wing 18 of
air stream has a lower pressure than the slower moving
air stream whereby the pressure differential in the former
the spider arm 1-1 a hollow de?ector cone 19 having
case is greater between the diffuser discharged air stream 50 a rear cylindrical portion 29‘ forming a hollow passage.
and the room air—thereby inducing more mixing of the
The de?ector cone 19 is mounted in the diffuser by spot
room air with the discharged air stream of the diffuser.
welding the inner surface of the cylindrical portion 20 to
Also, the faster moving discharged air stream creates
the outer edge of the depending wing 18 of the spider
more turbulence with the room air, thereby increasing
arm 11, as well as to similar wings on spider arms 12
the amount of induction of the room air into the dis 55 and 13 (not shown). The remainder of the de?ector
charged air stream.
cone =19 constitutes a trumpet shaped ?aring portion 21
The primary object of our invention is to reduce
forming a de?ector surface for de?ecting the supply air
smudging around the diffuser outlet with dirt particles
radially outwardly in a manner similar to the center cone
such as dust, smoke and the like from the room air
by providing a small, nonturbulent air jet having a lower 60
De?ector cones 14 and 23 constitute the de?ector
air velocity than the main jet of the diffuser in the area
members for forming the main or primary, radially out~
between the ceiling and the main air jet. This result
war-dly directed air jet of the ceiling diffuser. The air
is achieved by providing as the radially outermost an
de?ected radially outwardly therefrom constitutes the
nular passage in the diffuser a passage whereby the air
main air jet of the diffuser. The secondary air jet, which
?ow of the supply air stream supplied through the duct 65 flows between the main air jet and the ceiling, results from
connected with the di?user is emitted substantially ra
the provision of an additional, radially outermost de?ec
dially outwardly and parallel with the wall or ceiling at
tor member spot welded to the depending wing 22 on the
substantially right angles to the axis of the diffuser, from
which passage the discharged air stream is caused to take
spider arm 11, as well as spider arms 12 and 13 in a
similar manner (not shown). This de?ector member 23,
a lower velocity than the air speed of the main jet emit 70 which is concentric with cones 14 and 19 and the ring
ted from the remaining, more radially central portion of
5, is composed of a frusto-conical, axially forwardly ex
tending rear collar 24, which may be cylindrical instead
of trust-conical, followed by a trumpet shaped tlarmg
portion 25 and a radially outwardly extending portion 2a.
The outwardly extending portion 26 forms a convex
upper surface opposite the convex surface of the radially
outwardly ?aring portion 7 on the outer ring 5.
28 the radially outermost portion of the axially for
wardly ?owing supply air stream enters.
The velocity of the mam jet is greater than the velocity
of the supply air stream. This may be achieved by
making the areas at the downstream discharge side of
the passages 23 and 19 smaller than the areas at the up
stream entry side of said passages. For example,
arrangement provides an annular Venturi throat 27-—
referring to FIG. 2, the annular discharge areas, which
forming an annular restriction in the air passage space
are frusto cones formed by the lines A2 and A4 around
between the outer ring 5 and de?ector member 23. The
cross-section of the Venturi throat 27 is perpendicular 10 the entire periphery of the passages 23 and 19‘ and are
designated in FIG. 2 by the letters “A2” and “A4,” are
to the horizontal flow through the outermost air passage
less than the areas of the rings formed by rotating the
of the diffuser. It is the preferred form of restriction be
lines A1 and A3 about the axis of the diffuser, the latter
cause it is the best form for providing a smooth, uniform
giving the total area of the upstream, entry side of the
?ow in a horizontal plane. Also, the cross-sectional
area of the neck opening 28 at the upstream side of the 15 passages 23 and 19. By this area relationship, the ve
locity of the main jet is increased above the velocity of
Venturi throat is substantially less than the cross-section
the supply stream as the air ?ows through the passage
of the annular discharge opening 2? between the radially
outer edge of the de?ector member 23 and segment 8 of
23' and 19.
The invention is hereby claimed as follows:
ring 5 at the downstream or discharge side of the Venturi
1. A process for reducing smudging on a surface sur
rounding an air diffuser outlet which comprises supplying
While the annular Venturi passage above described
to the upstream side of a diffuser a supply stream of air,
will provide adequate reduction of the ?ow velocity of
de?ecting said air stream in said diffuser, discharging
the secondary air stream in most cases, it is also within
the major portion of the de?ected air stream as a main
the contemplation of our invention to use other means
to reduce said velocity. For example, an annular ring 25 jet from said diffuser in a radially outward direction gen
erally parallel with said surface at a velocity greater
3% may be welded about the upper edge of segment 24
to block off a portion of the cross-sectional area 28 to
further reduce the secondary ‘air jet velocity. Where
possible, we prefer however, to avoid protruding devices
than the velocity of said supply stream, and discharging
the remaining portion of the de?ected air as a secondary
‘air jet ?owing radially outwardly from said diffuser be
of this type because they create turbulence and interfere 30 tween said surface and said main jet at a velocity of said
secondary jet substantially less than the velocity of said
with the smooth air ?ow. Little or no turbulence in the
secondary air jet is desirable to give the secondary air
main jet and supply stream.
2. A process as claimed in claim 1 wherein said ve
jet its greatest throw (distance of travel along the ceiling
locity of said secondary jet is 50-80% of the velocity of
or wall) and minimize turbulent mixing thereof with
the main air jet.
35 said main air jet.
3. An antismudging air ‘diffuser for outlets of distribu
The employment of a Venturi throat passage in the
manner indicated thus provides a velocity decrease in air
tion systems comprising a hollow, radially outermost,
radially outwardly ?aring air ?ow directing member,
?ow at the downstream side of the outer annular passage.
It also has the advantage over other means for reducing
means mounted radially inwardly of said hollow, ra
?ow through the radially outermost, annular passage 40 dially outermost member and having a wall forming with
of providing a uniform, nonturbulent expansion of the
said hollow member a radially outermost annular pas
secondary air jet on the exit side of the Venturi throat
to provide a secondary air jet of reduced velocity in a
sage having an entry, upstream cross-sectional ‘area ma
terially smaller than the cross-section area of the down
horizontal plane parallel and adjacent to the ceiling
stream, discharge area of said annular passage, said means
45 de?ecting only the radially outermost portion of a sup
As a general guide, the velocity of the secondary air
ply stream of air fed to the upstream side of said diffuser
jet parallel and adjacent to the ceiling surface in the
into ‘a radially outwardly ‘flowing secondary discharge
area immediately surrounding the ceiling diffuser should
jet, and de?ecting means comprising at least one air de
fall Within the range of 50% to 80% of the velocity of
?ecting member mounted radially inwardly of said ?rst
the main jet of the diffuser. The reduction is ?ow ve
mentioned means ‘and having an ‘air de?ecting surface
locity through the outermost annular passage of the
for intercepting the remaining, radially inner portion of
diffuser can normally be provided by the greater cross
said supply stream and de?ecting said inner portion of
sectional area of the annular opening 29 over the cross
said supply stream radially outwardly into a discharge
sectional area of opening 28, but in some instances it
main air jet, said de?ecting means having a downstream,
may be necessary to or desirable to block off a portion 55 air ?ow discharge area which is smaller than the up
of the opening 23 in the neck portion to provide addi
stream entry :area of said de?ecting means whereby the
tional restriction of the entering air flow.
The invention herein described is most ef?ciently em
flow velocity of the discharged main jet is greater than
the ?ow velocity of said supply stream and the flow
ployed in round ceiling ‘diffusers where the radially out
velocity of the discharged secondary jet is less than the
wardly directed emitted air ?ow jets are substantially 60 flow velocity of said supply stream and, correspondingly,
uniform in all directions. However, the invention is
less than the ?ow velocity of said main jet.
also applicable, though with lesser degrees of success
4. An antismudging air diffuser for outlets of air dis~
as to uniformity of the antismudging in the ceiling areas
tribution systems ‘comprising a radially outermost, hollow,
surrounding the diffuser with rectangular or square
?rst ring member which ?ares radially outwardly from
diffusers. In the event an adjustable diffuser is desired, 65 a radially central opening in the upstream side of said
ring member, a second, hollow ring member concen
the cones 114- and 19‘ may be mounted so as to be adjust
able axially inwardly and outwardly of the ring 5 by
trically positioned in said ?rst ring member, said second
ring member having an opening in the upstream side
and ?aring radially outwardly in a downstream direction
outlined. in FIG. 2 of the drawing. The smaller velocity, 70 from said opening in said second ring member, said ?rst
and second ring members de?ning an annular, radially
relative to the velocity of the main jet, of the secondary
outwardly extending air flow passage therebetween, said
jet is achieved by virtue of the larger cross-sectional area
second ring member having in said radially outwardly
at the discharge end 29 of the radially outermost an
means now well known in the art.
The main jet and the secondary jet are ?guratively
nular passage 27 than the cross-sectional area of the
extending passage an annular convex surface, said ra
inlet opening 28 to the passage 27, into which opening 75 dially outermost, ?rst ring member having in said ra
dially outwardly extending passage an annular, convex
surface opposite said ?rst-mentioned annular convex sur
face, said convex surfaces de?ning in said radially out
wardly extending passage an annular Venturi throat there
portion of said supply stream as a radially outwardly
?owing main jet of discharge air, the total cross-sectional
area of said air-passage means at the upstream, entry
side of said passage means being greater than the total
between, the upstream, entry side of said passage having 5 cross-sectional area of said passage means at the down
a cross-sectional area substantially smaller than the cross
sectional area of the downstream, discharge side of said
passage to intercept and discharge radially outwardly
the radially outer portion of a supply air stream sup
plied to the axially rearward side of said diifuser as a 10
radially outwardly ?owing secondary jet of discharge air
having a velocity substantially less than the velocity of
said supply air stream, and air-de?ecting, air-passage
means spaced radially inwardly of said second ring mem
stream, discharge side of said passage means, Iwhereby
said main jet of discharge air has a velocity greater than
the velocity of said supply air stream.
References Cited in the ?le of this patent
Kurth _______________ __ July 20, 1954
Kurth _______________ __ Aug. 27, 1957
Germany ____________ __ June 16, 1931
Great Britain ________ .._ May 26, 1938
ber and positioned axially forwardly of said opening in 15
the upstream side of said second ring member for inter
cepting and de?ecting radially outwardly the remaining
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